text:
Why does an increase of airspeed result in a decrease of angle of attack?
In Chapter 02:  Aerodynamics of Flight of Helicopter Flying Handbook, on page 10, it says:

Induced flow velocity is increased, resulting
  in a decrease in AOA.

I don't understand how airspeed can change AOA. Looking at other posts on the topic, it seems that everybody assumes that to be true without an explanation. Can anyone tell me why?
PS: the statement above explains why there is a positive stall region in a helicopter's retreating blades when the rotor speed is too fast.

Depends on what's being held constant.  To maintain a constant amount of lift, less AOA is required at higher airspeed.  Or (in the case of a fixed wing), shove in the power, hold AOA constant, and start climbing.  Go back to your source and see what assumptions (or controls) are being applied -- is blade pitch being controlled so as to keep the lift vector constant?

@Holding Arthur my answer addresses the main question you seem to be asking-- do you also want to ask why changes in forward airspeed affect the angle-of-attack of the forward and retreating blades and may cause part of the rotor disk to be stalled?  That would best be a separate question I think.

@quietflyer You answer is good. Let's save that for another time.

On page 2-10 under the heading "Induced Flow (Downwash)", the book is making the point that if you have a wing moving forward horizontally at some fixed speed relative to the ground and some fixed positive pitch attitude relative to the horizon, and you surround the wing with a descending airmass, the wing's angle-of-attack will be less than if the airmass were not descending.  A rotor blade of a helicopter can be viewed as such a wing, at least at a given instant in time.
The book is using the term "induced flow velocity" specifically to refer to the downward velocity of the airmass caused (induced) by the rotor blades.  I.e., downwash.
The exact sentence you quoted was under the subheading "Out of Ground Effect (OGE)".  Since the ground is no longer acting like a "floor" to impede the downflow of air through the rotor system, you have more downflow than you would in ground effect.
If you were hovering in ground effect and the ground suddenly disappeared, the downflow velocity would increase and the angle-of-attack of rotor blades would decrease.

The induced flow is the flow pulled through the helicopter blades, which is largest in the hover out of ground effect.

Adding a vertical speed pointing straight down to the relative blade speed, decreases the angle with the resulting velocity vector.

To express it at the most basic level:

Lift is created by deflecting a flow of air downwards. Either a large mass of air is deflected a little or a small mass of air is deflected a lot.
The angle of attack controls (within limits) how large the deflection angle is.
Speed determines how much air can be deflected per unit of time.

The higher the speed, the higher the mass of air available for deflection. For the same lift, a higher mass of air needs less deflection, therefore, less angle of attack.

There's a small but significant mistake in the FAA handbook. As your airspeed increases there is a reduction in induced flow, resulting in a decrease in blade AOA.
Another way of thinking about it is to consider a fixed wing airplane as it speeds up. To maintain the same amount of lift as it accelerates, the coefficient of lift and angle of attack go down. The same is true for the advancing blade of helicopter.  Until you reach the bottom of the power required bucket the reverse flow region on the retreating blade is quite small and not too significant.


text:
Checkride and Basicmed
I am about to take my check ride, but my FAA 3rd class medical is still pending. I have not been denied, just jumping through some FAA hoops.
I have taken and completed the online course for basic med. Am I OK to take my check ride?
The only thing basic med asked is if I had applied for a FAA physical before... which I have.
I haven’t found much on this particular problem, so I’m looking for help. Any input is appreciated!

How did you get the required solo hours without sorting out your medical situation?

Welcome to aviation.SE! Can you give us a little more information? Which checkride are you doing (private, commercial etc.)? Have you ever held a 3rd class medical before? And note that the requirements for BasicMed include previously holding - not just applying for - a medical and completing a physical exam; doing the online course by itself isn't enough.

Closely related and a possible duplicate (?), depending on the details of the OP's situation

Unfortunately if you have never held a valid medical certificate since July 14, 2006, the answer is no.  One of the eligibility requirements for BasicMed is that you must have held a medical certificate after  that date.
§61.89(d) states

The holder of a student pilot certificate may act as pilot in command
of an aircraft without holding a medical certificate issued under part
67 of this chapter provided the student pilot holds a valid U.S.
driver’s license, meets the requirements of §61.23(c)(3), and the
operation is conducted consistent with the requirements of paragraphs
(a) and (b) of this section and the conditions of §61.113(i). Where
the requirements of paragraphs (a) and (b) of this section conflict
with §61.113(i), a student pilot must comply with paragraphs (a) and
(b) of this section.

§61.113(i) required that pilot hold a valid U.S. driver’s license, meet the requirements of §61.23(c)(3), and complies with this section and the conditions listed in §61.23(c)(3).
But §61.23(c)(3)(B) states that a person operating an a/c without a medical certificate under §61.113(i) must have:

At any point after July 14, 2006, have held a medical certificate
issued under part 67 of this chapter.

As such you will have to acquire a medical in this case before you can take the checkride.

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sort: votes


text:
Does the SyberJet SJ30 really exist?
It is amazing to think about a single-pilot jet with that much range. They have a site, they have some 2 minute videos talking about the aircraft... but there is no video of the thing flying or any review of its interior, no one talking about their experience of owning one...
Does SyberJet SJ30 really exist or is just a project that never made it off the drawing board?

Welcome to aviation.SE! This question is related.

Going off the Wiki definition, it does exist -- it just might be vapourware. Also worth mentioning that a ~2300nm range for a small-medium-sized twin-engine corporate jet isn't revolutionary; the Citation Excel has about 2150nm, while the newer Longitude boasts 3500nm, which is actually pretty crazy.

The Wikipedia page you linked actually includes a list of the various test and production aircraft. There seem to have been at least 9 production aircraft built.

It certainly seems to exist, at least in the sense that at least one has been built and registered. The Wikipedia article "SyberJet SJ30" contains a picture of one.
The registration number on the aircraft pictured is N7SJ, and the FAA's website says that that aircraft is indeed an SJ30.

The wikipedia article also claims 8 have been built so far.

in fact Wikipedia shows (currently) 2 photos of SJ30s in different liveries. While they might depict the same airframe, they might not.

It looks like 7 SJ30-2s are registered and one SJ30. https://registry.faa.gov/aircraftinquiry/AcftRef_Results.aspx?Mfrtxt=&Modeltxt=SJ30&PageNo=1

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text:
Is there any non-experimental way to obtain CL, CD, and CM as a function of the angle of attack and the control surface deflection angle?
I am working on a flight simulator for control algorithm testing. The issue I am facing is to come up with a relationship between CL/CD/CM and the angle of attack ($\alpha$) and the control surface deflection angle ($\delta$).
Since I'm developing a control algorithm for a flying wing, it is crucial to know how not only $\alpha$ but also $\delta$ affect the forces and moments on my flight vehicle. And I cannot afford to measure the forces and moments experimentally.
In the Gazebo simulator, the LiftDragPlugin's approach is to assume that the lift curve shifts up and down by $\delta$ times some constant. However, that is not the case, as can be seen from the numerical results from XFLR5 below.

Where “Plane Name $\pm\delta$” describes the curve for any $\delta$.
We can see that the curve shifts in both direction from zero-$\delta$ position. For instance, the stall angle decreases as $\delta$ increases.
My current approach is to construct a three-dimensional lookup table by using the curves at $-\delta$ and $+\delta$ as endpoints and linearly interpolate the two curves along the z-axis. When I need the aerodynamic parameter (CL, CD, or CM) at some $\alpha_0$ and $\delta_0$, I can just locate the point in this three-dimensional space from $\alpha_0$ and $\delta_0$.
Is this a valid way to determine CL/CD/CM as a function of $\alpha$ and $\delta$ numerically? If not, how should I approach this problem?

Where do you see stall in the data you presented? I don't see any stall. Using XFLR5 would be computational (i.e. numerical), not experimental.

I suggest that you take a look at JSBsim (http://jsbsim.sourceforge.net/)  While it is not a direct answer to your question, there are a lot of examples of JSBSim aircraft that could include some good data for you.

I’m not sure if XFLR5 can capture stall for a VLM analysis.

The graphs in the OP show fairly typical results that one would expect from linear analyses (e.g. VLM).
1. Lift
In the linear range, the lifting surface's lift coefficient ($C_L$) can be expressed as:
$$C_L = a_0 \alpha + a_1 \delta$$
where $a_0=\frac{\partial{C_L}}{\partial{\alpha}}$ is the lift curve slope and $a_1=\frac{\partial{C_L}}{\partial{\delta}}$ is the lift slope per plain-flap deflection, which are constants in the linear range and can be readily seen in your lift plot.
Conclusion: You can simplify your lookup tables to the above equations (all constants) if you are only interested in capturing the linear effect (which is all that VLM can capture anyway).
2. Pitching moment
In the linear range, you can express the pitching moment coefficient ($C_m$), which I assume is computed at quarter chord, as:
$$C_{m} = C_{m_{ac}}(\delta) + C_L\frac{l_{ac}(\delta)}{\overline{c}}$$
where $C_{m_{ac}}$ is the pitching moment at the surface's aerodynamic centre (AC) and is a function of $\delta$; $l_{ac}$ is the distance between the 1/4c and AC and is also a function of $\delta$; $\overline{c}$ is the reference chord length.
The $C_m$ plots you've shown seems to line up very close to the aerodynamic centre of the lifting surface (by the fact that there is very little change in  $C_m$ with respect to AOA). Flap deflection only significantly changes the offset ($C_{m_{ac}}$). The variations in the slopes are because you do not have a full span plain-flap (you have elevons which are partial span), which changes the spanwise lift distribution and the resulting aerodynamic centre.
Conclusion: You can replace your multi-dimensional lookup table to two 1-dim tables for $C_{m_{ac}}$ and $l_{ac}$, and supplant with the above equation. You may even replace these lookup tables with constant linear relationships if your plots hold water.
3. Drag
The drag coefficient ($C_D$) is the most interesting. It seems like there is some boundary layer analysis combined with the VLM, since $C_{D_0}$ changes per flap. If the Reynolds number do not change significantly, you can attempt the following simplication:
$$C_D = C_{D_0}(\delta) + K(\delta)C_L^2$$
where C_{D_0} is the form drag and $K$ is the induced drag factor, both of which are a function of $\delta$.
Conclusion: You may again simplify your multi-dim lookup tables to two 1-dim tables.
4. Lastly...
You definitely will start to see nonlinear effects at 30 deg control deflection in real life, maybe even at 20 deg. This is obviously not captured by VLM.

Thank you! The wing I analyzed in XFLR5 features a full span plain flap. I have not modeled the actual wing and the elevons that I want to simulate yet.

Ultimately, CFD (Computational Fluid Dynamics), i.e. computer simulation of the airflow and its effects on the wing, will do the job. Many such programs are available, including free ones.

For these kind of jobs VLM is nice tool or there exist some improved version of xfoil. CFD will be too advanced i think. You are in correct path


text:
How do head- and tailwinds affect airspeed?
I'm sure this was asked somewhere, I just can't find it. So if it's a dupe, let me know.
Anyway, I'm one of those guys that actually looks at the flight information when I'm flying. I fly transatlantic 3-4 times a year and they show it on the personal screens.
They display the groundspeed, headwind/tailwind, temperature etc. I'm wondering how to calculate the actual speed based on that. Is it the groundspeed plus/minus the headwind/tailwind? Meaning, if groundspeed is 500mph, and the headwind is 200mph, does that mean we're only traveling 300mph? Meaning it will take us 10 hours to travel 3000 miles? Or are there more factors involved and more math calculations?

Would this question over at Physics SE help to answer your question?

This question covers the difference between "GPS speed" (groundspeed) and airspeed. Does it answer your question?

How do head- and tailwinds affect airspeed?

They don't. Airspeed is the aircraft's speed relative to the air it's travelling through. The aircraft doesn't care whether that air is moving relative to the some other object such as the ground, because the aircraft is only interacting with the air.  (Similarly, when you walk to the back of the plane to go to the bathroom, you don't care how fast the plane is moving through the air or across the ground, since you're interacting only with the plane and not with the air.)

I'm wondering how to calculate the actual speed based on that.

Which actual speed? All of the speeds you mentioned are actual speeds. None of them is in any way artificial, virtual, or otherwise invented.

Is it the groundspeed plus/minus the headwind/tailwind?

That would be airspeed, i.e. the speed at which the plane moves relative to the air around it.

Meaning, if groundspeed is 500mph, and the headwind is 200mph, does that mean we're only traveling 300mph?

No. If groundspeed is 500mph into a 200mph headwind, this means that the plane has to fight against the headwind, i.e. its airspeed is 700mph.
Have you ever gone swimming where there is current? Can you imagine riding your bike on a treadmill?

Meaning it will take us 10 hours to travel 3000 miles?

No. If the groundspeed is 500mph, it will take you 6 hours to travel 3000 miles over ground.

But you deduct a headwind and add a tailwind, this aircraft would be moving 300mph over ground?

I don't follow. The OP said the groundspeed is 500mph. We don't need to compute it. We already know it.

@user13555 You deduct a headwind from airspeed to get groundspeed. If you're starting with groundspeed, you add a headwind to get airspeed. But you wouldn't do that unless you were using GPS to determine your speed and had no airspeed indicator on the aircraft, in which case you should be asking yourself if your plane is even airworthy.

When most non-pilots ask for the aircraft speed, they are usually wanting to know the groundspeed. This is the actual speed the aircraft is taking over the ground, hence it has already taken the wind into account.
If you remove the wind component from the groundspeed, you are left with the "true airspeed", which is the speed of the aircraft relative to the air around it.

If we take your sample problem of the aircraft flying at an airspeed of 500 mph and a 200 mph headwind (VERY strong headwind even for the jetstream but occasionally does happen) dead on the nose and steady, then, yes, your ground speed will be 300mph.  If wind is sustained for entire duration, then it will take 10 hours to fly 3000 statute miles.
Generally headwinds or tailwinds are not straight on the nose or tail, so a little trigonometry will be required to determine the direct headwind or tailwind component of the wind.  Let's say in the example above that you are flying at 500 MTAS on a ground track of 065 magnetic.  The upper level winds at cruising altitude are 200 MTAS coming from 081 magnetic.  Since the difference between your ground track and the wind is 16 deg, your true headwind component is 200 * cos(16 deg) or 192.25 MTAS, which will yield a groundspeed of 307.75 mph.
Modern flight and navigation software can compute this automatically for the pilot based upon a gps ground track, indicated airspeed, OAT and altitude.  Previously, graphical methods using an E6B flight computer were used to calculate this as well as headings to hold a course on.

My memory is failing me if they display the airspeed or groundspeed. Based on the other answers, it seems groundspeed already takes headwinds into account, so then it'll be easier to figure out length of flight etc.

Modern PFDs show groundspeed, true airspeed, and indicated airspeed, in different places. But the speed that appears next to the artificial horizon is IAS.

The Answer:
It's quite a common confusion when explaining speed to passengers - when someone asks "how fast are we going" they usually mean "how fast are we going over the ground" in which case you want Knots Groundspeed. This makes sense as both where you took off from, and where you land are (hopefully!) on the ground, and so it's your speed over the ground that determines travel time.
The Extra Bit:
Remember that Knots are Nautical Miles per Hour - so they don't correspond directly to Miles per Hour as you will know them. A knot is approximately 1.15 Mph, so if you were travelling at 500Kts, that would be 575Mph.
The Caveat:
Of course, this means that head/tailwinds can have a huge effect on your actual speed. If I'm flying at 500kts (airspeed) into a 100kt headwind, my groundspeed will only be 400kts.
I hope this helps!

"you want Knots Groundspeed" Honestly, you probably want to give the groundspeed in a unit the passengers are familiar with: (statute) miles or kilometers per hour.

A pilot once told me think of it like a boat in a current in a river. Even without the motor running if the current is 10 knots you will travel at 10 knots although technically the boat isn’t moving. Then you start the engine and travel at 20 knots plus the current speed = 30 knots.

To answer this question you need some aviation basics in speed measuring:
In aviation we use several different speeds whith different names.

KIAS (knots indicated airspeed) is the speed which is indicated in the cockpit. It's the aircrafts relative speed through the surrounding air. This speed is crucial for the flying performance of an aircraft 'cause it's the speed which is used to describe the minimum speed and similiar important airspeeds.
KTAS (knots true airspeed) is the corrected IAS. This speed is not important for your question so I won't go any further on that.
GS (groundspeed). This describes the aircrafts speed relative to the ground. So if an airplane has a groundspeed of 100kts it will fly 100nm per hour relative to the ground.
This speed is influenced by the head- and tailwind, the GS will be higher than the IAS/TAS if the aircraft experienced tailwind and vice versa.

So the answer is: the speed you, as a passenger, see at the IFE System is the groundspeed. Therefore it is already influenced by head- and tailwind and it shows the movement relative to the ground in nautical miles per hour (knots).

I know nothing about flying an aircraft, but on a recent trip on a Dreamliner to the Carribean I found myself regarding the very helpful maps and flight information accessible through the in flight entertainment system and puzzling over the expressions used such as ground speed, tail wind, head wind and wind speed. Cross winds weren't mentioned but I'm sure they could well have been.
Here's my layman's theory which made sense to me during the flight:
For passengers, the aeroplane's speed relative to the ground is the most important. It is ground cover we want after all, isn't it, to get us from home to our holiday destination and back in the most direct and efficient way possible.
However it seems to me that a moving aeroplane has two states:

a terrestrial state: when it is still in contact with the ground
airborne state: when it has left the ground

When moving forward for take off with its wheels still in contact with the runway a head or tail wind or indeed a side wind or an oblique wind will affect its motion as it would a car or any other terestrial vehicle designed to cover ground while remaining in contact with it.
However, once an aircraft has left the ground i.e. no longer has its undercarriage in contact with the runway, it is entirely at the mercy of the body of air in which it is suspended as it travels though it at several hundred mph. Here an aircraft experiences no more pressure on its nose cone at a constant speed through the air whatever the speed at which and direction in which the air itself may be travelling; head, tail or any other 'winds' surely become irrelevant; although the speed at which the body of air may be travelling is extremely relevant.
For example, if the body of air supporting the aeroplane is travelling at 50 mph in the same direction as the aircraft which is doing 400 mph the ground speed will be cumulative - namely 450 mph but the plane will still only be doing 400 mph relative to the body of air in which it is traveling. If the body of air has a terestrial speed of say 100 mph in the opposite direction to an aircraft travelling at 400 mph, the aircrafts speed relative to the ground - its ground speed - will be subtractive - only 300 mph.
If the body of air in which the aircraft is suspended is moving in a sideways direction' either directly or obliquely, relative to the terestrial course the plane needs to follow in order to describe a relatively direct route from take off to landing the plane won't be 'blown' off course as such but if no corrections are made and if all speeds are steady then the aircraft will arrive at a different destination from the one intended.
For example if an aircraft maintains a steady speed of 500 mph with respect to the ground i.e. has no help or hinderance from the body of air which is supporting it moving in a favourable or unfavourable direction but has a direct sideways motion of say a steady 20 mph left to right and the distance of terestrial travel is 2000 miles, after the plane has travelled for the 4 hours necessary to cover the 2000 miles it will arrive 80 miles to the right of its desired destination.
In these same steady conditions the plane would need to aim at a point 80 miles to the left of its desired destination and then it would arrive at its desired destination. The tail, head and cross winds are a different story though once the (for all intents and purposes) static ground is about to come up and meet the aircraft at considerable speed and as it prepares to leave it's airbourne state and assume its terrestrial state.
It's then, I guess, that the boffins invoke their equations for approach speed relative to the ground, air movement speed - be it head, tail or side wind and runway length in order to make the transition to a smooth landing.
I know this forum is to answer a specific question; please accept this as the offering of a complete layman but it does seem to me to be scientifically sound - indeed is my own answer to a question I have asked myself but I think this would appear to cast some light on the role head or tail winds play in aviation scenarios.

I would highly recommend editing your post to improve the formatting, a big mass of text is hard to read. It has been flagged as low quality and it may get removed if not improved.

Hi chris dolman, welcome to aviation.stackexchange. Your text is very hard to read because of the lack of formatting. If you allow me, here is some advice for writing better answers: 1) be to the point; side stories about going to the Caribbean, past work experience, are not relevant to the answer. 2) Cut your answer up into a number of paragraphs of at most 4-5 sentences. Leave blank line spaces between the paragraphs. 3) If you are not really sure about the topic, it's better to restrict your answer to what you know. If you are unsure about some parts of the answer, just state that.

Hi chris dolman: I've improved the formatting and changed a couple of sentences to save your answer from being deleted by the community. It could do with further improvement, but I leave that up to you. Again, welcome at aviation.stackexchange.

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text:
Do employers prefer to hire younger pilots?
Do companies, regardless of country, tend to shy away from hiring older low-hour pilots? "Older" meaning mid-30s to early 40s.

Yeah, they can pay them less; this doesn't just apply to pilots.

Saying "regardless of country" makes this extremely broad. Different countries can have very different policies or economic conditions that affect who they will hire as pilots. "Companies" is also very broad, as this would include everything from large airlines down to small charter or corporate operations.

Older people generally demand higher quality of life and will not work for peanuts when better options are available, including leaving aviation to pursue better careers.  Younger pilots will generally work for less, take more risks, work longer hours, and fly junk planes just to gain hours to move up the ranks.  They are just easier to employ.

The answer to that has varied throughout airline hiring history.  There was a time when you'd better be young or else your chances of getting hired by the majors was essentially nil.  Now, "age discrimination" is a thing, and at least officially (in the US, at least) it is probably against policy to treat the 30 year-old ATP with 2000 hours differently than the 50 year-old ATP with 2000 hours.  (Or the 30 year-old commercial pilot with 500 hours different from the 50 year-old pilot with the same resume.)
These days, the regional airlines in the US seem to be so desperate for pilots that if you meet the minimums, it's more a matter of scheduling a class than it is scheduling an interview.  So if you're willing to fly for a regional, even the late 40-something pilot can probably get on with an airline.
Interestingly, this dynamic has its roots in the hiring practices of 30-40 years ago, when the airlines hired large numbers of "young" pilots -- meaning that the senior ranks of many majors have lots of pilot who are close in age and who are now reaching the Age 65 mandatory retirement all together.  This creates significant vacancies at the majors, who draw their new-hires from both the military (which is a fairly constant supply) and from the regionals (which has become where the "slack" has been that is now getting picked up).  The massive demand for hiring into the majors translates into regional captains moving up, and thus out of the regional airline far more rapidly than in the past.  This drives upgrade times at the regionals down, and has put pressure on their hiring departments to keep the right seats filled.
Quite literally, I was recently told that the "hiring" process at one regional has become nothing more than a confirmation that the candidate does meet the basic minimum qualifications (commercial license, 2nd class medical), and scheduling a class date.  If they pass the training, they're hired.
That is a snapshot in time in one country; throughout history that sort of a process is anomalous if not unprecedented.

There are the Aeronautical Science colleges which also provide a source of young pilots for First Officers.

@SMSvonderTann Such graduates will be going to the regionals, not the majors. Moreover, such graduates will still need at least 1000 hrs, so will almost certainly have worked at least one (from my observation, usually 2+) flying jobs first before being eligible. It really isn't accurate to suggest that someone with an aeronautical science degree is going to go straight to any airline after graduating, if that is what you meant.

@JonathanWalters I thought it was only 750 hours for an ATP-r for graduates of such programs. I was just adding that on as another way of pilots getting into the industry.

@SMSvonderTann  750 for military pilots, 1000 for graduates of approved 4 yr colleges.

@SMSvonderTann   The majors want to see turbine PIC time on a resume, which means that somebody trusted you with their jet or turboprop for long enough that you've had a year or several flying it as the captain.  Nobody coming out of the 4-year programs has that, unless they flew daddy's King Air on the weekends.  Those colleges you mention are a great route into the regionals, but not into the majors directly.

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text:
Are there any airports whose budgets are in the public domain?
Most airports - at least in India - are privately owned. AFAIK, even the ones which are owned and operated by the government (i.e. managed by the Airports Authority of India) do not make any financial numbers known.
Are there any airports whose records are in the public domain (even if they are small island airports)? I'd like to have some idea how things work, even if it's only about a small airport.

Are you asking only about airports in India, or would be you interested in seeing the numbers for an airport in another country?

Singapore Changi does publish its annual report.

2015 Financial report for KMCI pdf

Budget and capital plan for KSFO.

This varies heavily by country but I can answer this for the United States operating under the FAA/General US legislation (which varies by city).
Here in the US some airports are owned by the local government (there are also privately owned/publicly used and fully privately owned airports). Publicly owned airports (owned by cities/towns/localities etc.) generally either publish their budgets or you can obtain them if you request it. For example if you want to see the information for KPNE or KPHL (owned by the city of Philadelphia) you can submit a form to the city and request the information. Every city is a bit different and there may be small processing fees/long wait times but generally the records can be obtained.
The FAA also published a lengthy brief on the cost-benifit analysis of having an airport in your area. It sheds light on some common costs and such.
Keep in mind that the airport while owned by the city and operated by the city, often has many private companies on its premises that simply lease a building or plot of land. The budgets to operate these FBO's, service centers and the such are more than likely private information.


text:
How do Rapid Exit Taxiways improve aircraft movements?
I have been reading about Mumbai Airport (CSIA) (IATA: BOM ICAO: VABB). On it they mention:

The airport has two intersecting runways. Both runways have been
  upgraded to Code F, which means they can accommodate larger aircraft
  like the Airbus A380. Following a presentation in March 2011 by UK’s
  air traffic service provider NATS on how the capacity of the airport
  can be increased, MIAL set a target of 48 aircraft movements an hour
  in an effort to reduce congestion at the airport. Both runways were
  operated simultaneously especially during peak hours to try and attain
  this target.MIAL scrapped simultaneous Cross-runway flight operations
  in mid-2013 after it found that single runway operations were more
  effective for increasing Aircraft movements per hour. Runway 14/32 is
  now used only when the main runway is unavailable due to maintenance
  or other reasons. The construction of new rapid exit taxiways helped
  in increasing flight handling capacity from 32 movements per hour to
  44 in 2012.

Can somebody share what are these rapid exit taxiways and how do they help to increase flight handling capacity ?
I did see the OSM page and was able to get this -

Maybe that could help in explaining what is being told to us. Have given/shared a more detailed diagram that I could find from OSM.

Also it would be nice if a sketch/diagram of how these rapid taxiways are laid on CSIA or failing that a diagram of any airport having similar/more/less number of rapid exit taxiways would be good too in order to understand how they work.

See this related question.
Rapid exit taxiways (or high speed exits) enable aircraft to leave the runway at speeds up to 50 or 60 kts depending on the runway and aircraft type (50 kts even in wet conditions).
They have a long, constant radius rather than a 90 degree turn.
You might find this FAA presentation useful.

Source: airlinepilots.com forum.
The purpose is to enable a landing aircraft to vacate the runway more quickly without having to slow down to "normal" taxi speeds.  A large aircraft like a 777 might need to slow to 10 or 15 knots to take a right angle turn.  This would mean spending longer on the runway slowing down to that speed.
Since the aircraft next on the approach cannot land until the runway is clear, this enables closer spacing of landing aircraft.
Aircraft type, airport restrictions, operator standard procedures and weather can all impact what "high speed" means but it is always faster than the 90 degree turn.

How does the speed for 150° turns compare with 90° turns? Can it potentially cause more congestion on the taxiways while reducing congestion on the runway(s)?

@gsnedders Think of it like a highway. You can exit a highway onto a curved ramp at 80 mph, no problem. Try doing that with a sharp 90 degree turn and you're going to have a bad day. The same is true when 'driving' an airplane on the ground. As far as congestion on the taxiway, that's not really a big concern. Many planes can occupy the same taxiway, but only one can occupy the runway at a time (with the exception of "line up and wait.")


text:
What time window size the Eurocontrol's IFPS considers when comparing the EET informed by the airline and its own calculated EET?
Excerpt from IFPS Users Manual Ed. 22.0 (chapter 34. PROFILE CALCULATION/ROUTE ANALYSIS):
In addition, whenever present in a message, the estimated elapsed time(s)
(EET) shall be used by the IFPS for profile calculation, together with the
total elapsed time (Item 16B). Prior to using the EET information, the IFPS
shall validate it against its own calculated EETs allowing for the provided
EETs to be within a pre-defined window around the EETs as calculated by the
IFPS. In the case the provided EET information is found to be outside this
window, the message shall not be invalidated. In this case the IFPS shall
retain its own calculated EETs.

What is the size of the aforementioned pre-defined window?

This window is expressed as a percentage. I read a French tutorial about CFMU, which may still help, in which error PROF 191 was issued as "PROF191: TTL_EET DIFFERENCE > 40%, CALCULATED TTL_EET FROM LFRS TO LFLB = 0101 (HHMM)", making me believe this could be 40%.


text:
Is it possible to split a NOTAM in two messages in case it is too long to fit in a single message?
Would it be in accordance with ICAO norms to issue two different NOTAMs with the same year, series and number regarding the same subject and informing //PART 1 OF 2 PARTS// and //PART 2 OF 2 PARTS// in the NOTAMs bodies to inform that they are parts of a single NOTAM?

Have you considered that a NOTAM might not be the best choice for promulgating such a lengthy tome?  Perhaps editing for brevity may be the answer here, or reconsidering if it is worthwhile to feed to hapless airmen the world over?

I understand that a NOTAM should not be that long and that it should be edited for brevity. Still, I would like to know if it would be in accordance with ICAO norms to issue two NOTAMs with same year, series and number if they refer to the same subject.

I have seen it done before but i forgot where.

Multi-part NOTAMs seem to be part of ICAO standard, as far as googling reveals. I can’t seem to find a definitive reference though.
An example - and from experience a relatively reliable one - for a multi-part NOTAM is the infamous Sydney crane list, at time of writing in NOTAM H6002/18, which at the moment comes in three parts and has the part listing in field A):

H6002/18 NOTAMR H5974/18
  Q) YMMM/QOBCE/IV/M/AE/000/999/3357S15111E008
  A) YSSY PART 1 OF 3
  B) 1811190334
  C) 1811300500 EST
  E) OBSTACLE CRANES AT FLW LOCATIONS
  239FT AMSL BRG 002 MAG 1.58NM FM ARP
  497FT AMSL BRG 002 MAG 3.82NM FM ARP
  220FT AMSL BRG 002 MAG 1.38NM FM ARP OBST UNLIT
  413FT AMSL BRG 003 MAG 3.09NM FM ARP
  410FT AMSL BRG 003 MAG 3.14NM FM ARP
  577FT AMSL BRG 003 MAG 4.65NM FM ARP
  685FT AMSL BRG 004 MAG 4.26NM FM ARP
  249FT AMSL BRG 004 MAG 2.98NM FM ARP
  413FT AMSL BRG 004 MAG 3.18NM FM ARP
  224FT AMSL BRG 005 MAG 1.53NM FM ARP OBST UNLIT
  500FT AMSL BRG 005 MAG 3.42NM FM ARP
  953FT AMSL BRG 005 MAG 5.26NM FM ARP
  623FT AMSL BRG 006 MAG 4.54NM FM ARP
  PART 1 OF 3

Found at FAA pilot briefing site.

Also an example of the nigh-incomprehensibility of NOTAMs.

As a railroad person who's seen many a hard-to-read train order, I recognize I'm looking at an extreme case, but still.  That would never pass muster on rail: firstly the topic would be an Order or Notice in full page format. But even as a train order, it would require deployment of a technology (invented by George Westinghouse) called the "carriage return" or "newline".  I am unable to demonstrate here in a comment.

To be fair, everywhere I‘ve seen this NOTAM, the carriage returns were in the right places. I couldn’t get them to work in the quote on the iPhone app, though.

The standard US stadium security NOTAM is three parts too. Greece and Turkey like to carry on an entire diplomatic spat in the NOTAM database. The NTSB chair recently called the system "messed up" and "garbage" thanks to this kind of nonsense.

Now that carriage returns are live, it's more comprehensible, but not much.

For next time, you can enter "newlines" with ""


text:
How can ballistic techniques be used for passenger transport?
Going anywhere on the globe in half an hour, instead of up to 29 hours, is of course very appealing. How can ballistic technology be used for the purpose?
The acceleration is supposed to not exceed that which is acceptable for humans.
The problem of radiation in space is assumed to be solved elsewhere.
If you need an image of what this is like imagine a space rocket with astronauts that instead of reaching an orbit is falling down at a desired destination.
The Stratolaunch is an example of such a system where an aeroplane is used in the atmosphere and rockets beyond that into space.

I would miss the journey, the experience and the story to tell. In thirty minutes across the globe is like instant beaming. If we get ships with overlight speed as replacement, okay ;)

Across the globe in 30 minutes means you'll arrive at your destination dead. Or you'll have to do some major fighter-pilot training and be in peak physical condition. The kinds of G-forces involved would kill most of the traveling population.

There are companies studying hypersonic travel but are probably going to be less like ballistic missiles.

Commercial suborbital flight is dawning on the horizon, however, the G forces are much less than ballistic missiles or giant cannon shells for that matter (we did not go to the moon that way). However 0 drag space flight would be an interesting study for fuel efficiency. For example, 12,500 miles suborbital vs Concorde.  Bottom line, longer, slower burn on rocket to keep Gs survivable for humans.

@RobertDiGiovanni Where is any such study of fuel efficiency?

Welcome to Aviation Stack Exchange, and interesting question. I assume you know something about the ballistic process for vehicles such as ICBM's and so I'll start my explanation from there.
Firstly, ballistic anythings don't account for the acceleration's effect on humans. Only machinery and weaponry has been transported in this manner, and I don't see ballistic missile technology becoming well adapted for this purpose anytime soon. Just look up the acceleration values for a Trident III for example, and you'll quickly see that you and I would definitely not want to get on one of those.
Secondly, ballistic technology is single-use. Missiles obviously have a terminal point, where it blow up as it were, but an alternative like rockets and space shuttles present a more suitable option for us humans. At a much shallower trajectory than ballistic missiles pose, space shuttles provide a fast, but highly inefficient method of travel that we rarely use anymore, and most definitely not for mass commercial purposes.
Long story short, ballistic missiles specifically would not be suitable at all for humans, if we want to board and disembark alive. Some new options, such as the Sabre rocket/aircraft are promising new technologies, but for our safety and efficiency, traditional aircraft are still the prime choice.

The word missile is no longer mentioned in the question due to downvotes and closing. Slower acceleration would be needed for human transport and this is not impossible. Please show how pushing something through air can have higher "efficiency" than transport through vacuum.

@DavidJonsson, well, before you can push it through a vacuum you have to first push it through air, right?  Getting to that vacuum at the comfort level of a paying passenger is no small feat…


text:
What is the regulatory definition of AOG?
What is the legal or regulatory definition of AOG (Aircraft on Ground)? For example, this is sometimes stamped on a repair order.

There is no regulatory definition of the phrase "Aircraft On Ground" as used in work orders or repair orders in the FARs (14CFR), it is used by convention to indicate that the order is urgent as the parts or repairs specified must be completed in order to fly the aircraft.
What causes the aircraft to be grounded can be a functional issue that (such as a damaged control surface: The aircraft is grounded until it's repaired or replaced) or a regulatory one (for example, an airspeed indicator is part of the Day VFR required equipment, if it fails even though the plane can physically fly it's not legal to do so - your new airspeed indicator would be an AOG parts order).

AOG is usually used to hurry up and easy the procedures such as for example the Customs Clearance, AOG stamped cargos are given high priority and so on


text:
Do noise abatement procedures have an impact on aircraft emissions?
The ICAO has imposed Noise Abatement Departure Procedures (NADP1 and NADP2) in order to limit the noise impact of departing aircraft on communities living nearby airports. Could noise reduction lead to an increase in NOx/CO2 emissions (an aircraft needs more power to achieve faster climbing rates)? If so, why don't the ICAO (or local authorities) impose "Emission Reduction Procedures"?

Because, if your theory is correct (and I don't know the answer to that part), people really care far less about emissions than they care about being kept up all night by aircraft taking off from the local airport.

This document (Appendix B) points out "significant tradeoff
issues [...] between noise, NOX and CO2, primarily related to the thrust-settings". It looks more complex than I thought (http://www.sustainableaviation.co.uk/wp-content/uploads/2017/03/FINAL__SA_InterDependencies_2017.pdf)

Generally, it is most fuel efficient - when considering fuel for the whole flight as opposed to individual flight phases - to climb to cruise altitude as quickly as possible (i.e. using maximum thrust), since the aircraft flies much more efficiently at cruise altitude than at lower levels. This is in direct contradiction to anything to do with close-in noise reduction (i.e. around the airport), but it would reduce total flight emissions (other than noise).
For noise further away from the airport, climbing with maximum thrust may actually be more beneficial, as there is another tradeoff between noise emitted at the aircraft and the altitude achieved at the noise sensitive area (quiet can mean passing with low thrust or at high altitude).
So, yes, by altering the climb profile, the emission profile for the flight is altered. The noise abatement procedures will often lead to higher emissions than could be achieved theoretically (not necessarily practically though).


text:
Which pilot license is required in the US to engage in glider towing?
As a former member of a US glider club (I live in Europe now, and it's all winch launches), I always thought being a tow pilot was a good way to build time. Can a private pilot tow gliders in exchange for money or credit with the club, or is a commercial ticket needed?

Are you specifically interested in whether the pilot can receive payment or requirements in general?

I'm in Canada and the only requirement at a private club is a PPL, and beyond that whatever the glider club requires (which will in part be based on insurance requirements).  Usually clubs want around 75-100TT with a tailwheel checkout of 5 hours or so.  For EASA, I believe they now have a towing rating of some kind, which you would probably get as a member of a club.  Google "EASA glider towing".  At a commercial glider center, common in the US, I believe may require a commercial license, but I think in Europe and UK like Canada it is almost all private clubs.

In the US a Private Pilot can receive compensation. Not sure about Europe. See the FAA Legal Interpretation for Umphres. https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2010/umphres%20-%20(2010)%20legal%20interpretation.pdf

A private pilot certificate is the minimum required.  In addition you need the following experience and endorsements to be current:
CFR, part 61, section 61.69, outlines the requirements for towing privileges.
You must:

1) Hold at least a private pilot certificate with the appropriate
  category rating;
2) Have logged a minimum of 100 hours as pilot in command in the same
  category aircraft used for towing;
3) Have a logbook endorsement from an authorized instructor certifying
  you have received ground and flight training in gliders or unpowered
  ultralight vehicles, and is proficient in the areas listed in part
  61.69(a)(3)(i)(ii)(iii) and (iv);
4) Have a logbook endorsement from a pilot that already meets the
  requirements of part 61.69 (c) and (d), who has accompanied the pilot
  on three flights which has certified them to have accomplished at
  least three flights in an aircraft while towing a glider or unpowered
  ultralight vehicle, or while simulating towing flight procedures; and
  In the preceding 12 months has performed three actual or simulated
  tows accompanied by a qualified pilot or has been towed for three
  flights in a glider or unpowered ultralight vehicle. In accordance
  with part 61.52, pilots towing under an ultralight exemption may
  credit experience obtained in ultralight vehicles for their towing
  experience and endorsements.

Added per comment on question above:
Yes, a private pilot can be compensated for glider towing.
https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2010/umphres%20-%20(2010)%20legal%20interpretation.pdf
Source: https://www.faa.gov/licenses_certificates/airmen_certification/sport_pilot/media/towing_req.pdf

Could you address the part about whether the pilot can receive payment?


text:
Where can I find a database of SIDs, STARs and approaches?
I am investigating SIDs, STARs and approach procedures. I have a couple of questions about it:

Is there a way to get SID, STAR, and approach data from airports around the world? I don't mean from the AIPs but rather from a database.
Is there a way to simply calculate (some algorithm maybe?) and reproduce the shape of the legs of such trajectories? I mean some sort of simplification in order just to have an idea of what SID, STAR and approaches look like.

I don't have a source for data, but procedures are initially designed as text with type of leg, distance, lat, long as segment descriptions, so it's not a problem to derive the graphic representation. Description elements are compliant with ARINC-424

Do you mean just the name of SID,STAR,APPROACH of each airport or every steps contain in those procedure?

Every leg and waypoint, constraint, etc. You may search for "procedure design arinc-424" for documentation, e.g. this ICAO one. Also FAA Order 8260.19.

I don't completely understand your question (and maybe it should be two questions). For a data source, see this question; the typical way to get this data is from the AIP or a data provider like Jeppesen. For the second part, I don't really understand what you mean by visualizing the procedures; they're published in a graphical form already (at least in the US).

Maybe for the US, the database is Coded Instrument Flight Procedures (CIFP). Formerly known as the National Flight Database (NFD). It can be downloaded following the links provided.

For the US see https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/

@mins well as far as i know graphic representation depends on aircraft type, weather, performances... therefore their shape changes considerably and trajectory shape prediction is very complicated and tough.

@vasin1987 I mean every step (latitude and longitude) contained in the procedure

@Pondlife semplified question: get data -> calculate points coordinates -> plot shape of procedure.... eventually my goal is to create something like in the charts

"graphic representation depends on aircraft type, weather, performances..." I thought I understood your question, but now I'm lost. Standard procedures graphically depicted on "plates", except for category minimums are the same for all aircraft. I'm not talking about prediction of actual path.

@mins So how can they depict standard procedure graphically if their shape changes based on many parameters (weather, perform....)?

"if their shape changes based on many parameters (weather, perform....)", I don't think the shape changes. Do you have a document which says differently?

@min The shape does change indeed... FMS output is a pretty good proof of it... imagine same airplane having minimum take off weight and then maximum take off weight... different rate of climbs may occur thus generating a different calculation of conditional waypoints (described by the way in the ARINC 424)

As mins says, the "shapes" do not change for different aircraft. The waypoints are all fixed lat/long and the crossing restrictions are all the same. Depending on aircraft capabilities, equipment, etc. they may use different approaches. For example the ILS approach will usually be separate from the RNAV approach. SIDS/STARS may have a couple of different options depending on turbojet or propeller, but they will both be part of the procedure and depicted on the same plate. If we can understand how you're wanting to use it we can probably help you out.

Secondly, there is probably no single source for data for all countries. All countries disseminate information in a different way. The only people that compile all the separate countries into one source do it for profit. Jeppesen will have pretty much the whole world in their database, but that's what they do for a business so you have to pay. Garmin, etc will have all that info for their products, but it will be proprietary

Hello @TomMcW thanks for the answer but I have to desagree: shapes of SID/STAR/APPROACH do/can change. As a matter of fact the points  forming the procedures are not always fixed... I deal with FMS pretty often and I know for sure that there are algorithms that calculate points coordinates during procedures... you can see this at the attachment 5 of the ARINC 424... that's why I am asking the question... is there a way to simplify/avoid the calculations and get some sort of approximation

The fixes within the database do not change. What will change are the transitions between legs and certain performance based fixes (altitude terminated legs, etc). Leg transitions are affected by a/c ground speed and the current winds. Algorithms to compute these are specific to each FMS and aircraft type. Performance based fixes depend on the a/c performance database provided to the FMS by the a/c manufacturer.

@Gerry The fixes within the database can change throughout the years

The fixes will change when the procedure changes - which they often do. That's why the database is updated every 28 days. The FMS does not move any of the procedure fixes contained with the database when constructing the path.


text:
How do pilots calculate the temperature to put Into the FMS for an FLX takeoff?
I recently read an article about derated takeoffs and I understand the concept, but how do pilots know what temperature to put into their FMS if they want an FLX takeoff? Some people say it's a rough estimate like ~50-60 C, but is this true? If it is gauged by some external factor, what is it?

Related: In the Wikipedia article you link, there is a reference to Assumed Temperature Thrust Reduction. In this document there is a section for How To find an Assumed Temperature which includes a table. Derated T/O and flex are not the same (derated means an engine optimized for a fixed lower thrust in actual conditions).

For Airbus Aircraft you use a tool from Airbus where you put in data like wind, air temperature, pressure, weight, runway characteristics (length, heading, elevation, etc)  and other elements that calculates the flex temperature. It also gives you some other parameter like required runway length among others.

Welcome to Aviation.SE!

The principle is that you run the take-off distance calculation in reverse.
There are tables or graphs in the QRH that tell you what runway distance you need for take-off given the pressure, altitude, temperature, head-wind, cross-wind and runway state (dry, wet, snowed…). And you put in all the other numbers and then look up the highest temperature that make you still fit in the runway distance actually available, usually with some margin. Or the highest temperature allowed—you don't derate below the normal climb thrust.
These days most pilots will have an "electronic flight bag", an application on notebook, tablet or in newest aircraft even built-in computer in cockpit, where they'll put the numbers and it will look up the values for them. But the principle is still the same: find the highest temperature for which the available runway is sufficient.


text:
Radio communications lost on climb out in IMC: when can I turn on course?
Let's assume:

I have been cleared direct from Knoxville Downtown (KDKX) to London-Corbin (KLOZ) at 6000ft. The direct heading is 357°.
I lose comms after take off from runway 26, I squawk 7600 and I'm in IMC
Assume I cannot land where I took off

My plan is to climb to 6000 as filed but I can't turn northbound on course because of obstacles. When can I turn on course? Is the proper procedure to fly the back side of the localizer westbound till I reach 6000 and then turn?

I believe the proper procedure is to continue as cleared/filed unless there is some other kind of emergency that requires you to turn back. For altitudes, you do either the assigned altitude, expected altitude, or minimum enroute altitude. If your comms radios fail, try listening to nearby NDB/VOR's because ATC may try to contact you over them. You may not be able to respond, but you can still comply/signal through turns or ident.

See AIM Section 4: 6-4-1 and FAR 91.185

This is almost a dupe of this question

Assigned. Vectored. Expected. Filed. flown at the highest of the min. enroute, expected, or assigned altitude.  Otherwise, anything you, as pilot in command, determine is appropriate to meet the situation.

That is what I said on the oral. However, wa

Mike, what was the exact takeoff clearance that you were given?  Often, clearances from uncontrolled airports like this include something like " upon entering controlled airspace cleared direct to..." or some other specific clearance issued as part of the takeoff clearance.

Your assumptions are insufficient.
If your clearance just states "CLIMB 6000 direct", and there are obstacles along the route, you have been given an incorrect clearance.
It should have included the phrase "EXPECT" and an altitude and possibly also a time that would permit you to clear the obstacles.
Also, from your Skyvector link, it looks the Direct course parallels V97 very closely, which has an MEA of 5000, so you should not encounter any obstacles at 6,000.  Once you reach your clearance limit LOZ, you may initiate the approach.

Nevertheless If you lose comms you are expected to climb to the highest altitude of:

Your last clearance altitude
Minimum IFR altitude.
The altitude you were told to expect

No, you will squawk 7600 and continue on your flight plan to your destination as filed. The airspace has already been cleared for you during your flight time.

This is not correct. If he got "cleared direct" he has been issued an amended clearance, which is what ATC expects him to fly

This answer, while technically correct, isn't helpful because it doesn't address the main question of obstacle clearance.

The obvious answer is: turn on course when you can safely do so. In reality, though, you - hopefully! - shouldn't find yourself in this situation anyway, because it would mean that something strange happened with your clearance.
Your question is a bit unclear because you didn't say exactly what the full departure clearance - or most recent clearance - was but as far I know "cleared direct KLOZ" isn't a valid departure clearance. The ATC orders (section 4-2-5) say that "cleared direct" is only used for amending a previous clearance and ATC must include the route of flight in your initial one (section 4-3-2):

d. Route of flight. Specify one or more of the following:
1. Airway, route, course, heading, azimuth, arc, or vector.
2. The routing a pilot can expect if any part of the route beyond a short range clearance limit differs from that filed.

So your departure clearance should have both the clearance limit (KLOZ) and the route, maybe something like this:

N12345 is cleared to the London-Corbin airport as filed, via radar
  vectors, then direct. Altitude 2500, expect 6000 within 10 minutes,
  departure frequency 123.9, squawk 1234. Clearance void if not off before 1200Z.

Obviously the details may be different, but the point is that if ATC didn't give you specific instructions on the initial route - even if it was just to expect vectors - then you should have asked for them. Otherwise you're taking off into IMC with no idea which direction to fly in. KDKX is uncontrolled and there's no tower to give you an initial heading after takeoff, but it would be surprising if you didn't get something in your clearance, considering that taking off from 24 puts you under McGhee Tyson's class C almost immediately.
But let's say that you got the clearance I mentioned above and your comms failure happens after you enter IMC but before you can contact Knoxsville Approach for your vectors. 14 CFR 91.85 says you should fly:

If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance;

And:

In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.

That means ATC will expect you to fly directly to KLOZ but obviously they don't expect you to fly into a hillside or transmission tower if it's in your way (and they know as well as you do that those obstacles are there). As PIC you have to make a decision on what the safest thing to do is in the situation, considering the class C nearby, any traffic you heard (or can still hear), local weather conditions and your aircraft's capabilities. Personally, after squawking 7600 I would make a left turn back east - to remain clear of the class C and the towers NW of the field - and climb over or east of KDKX until reaching a safe en route altitude. Then I would continue directly to KLOZ as filed, still climbing if necessary to reach my cruising altitude. But that's just one option, another 'obvious' one would be to fly the published ODP:

Rwy 26, climb heading 245° to intercept VXV R-275 to 3100 before
  proceeding on course or for climb in visual conditions cross Knoxville
  Downtown Island Airport at or above 3300 before proceeding on course.

But if I hadn't briefed the ODP - which I should have, especially in relatively low IMC - because I was expecting vectors, there's no way I would try to dig it out and brief it on the spur of the moment.

as far I know "cleared direct KLOZ" isn't a valid departure clearance -- not correct at all. Box 8 on the Flight Plan can have the word "DIRECT" for aircraft properly equipped.  You'll get "via departure procedure, direct". Have done this all the time /G aircraft.

@rbp Yes, I've been cleared direct when /G too. But as far as I can remember, I've also always been given an initial heading or been asked what heading I plan to fly. Or, as you said, been given a DP to fly. And that's what I was really trying to say: being cleared direct with no instruction or request for an initial heading seems really odd to me. But maybe you've had different experiences from me, I think a lot of practical details depend on where and how you fly.

pond -- I completely agree. that being said, if you are departing IFR from an uncontrolled field, and there is no obstacle departure, then you fly what is called a diverse departure, which means you can climb out in any direction so long as you meet the ROC requirements for IFR for the Part you are flying. See  https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/Chapter_1.pdf (p. 1-14)

(con't)  That means that if you file from ABC airport to XYZ airport, Direct then when you phone FSS to pick up your clearance, you should just get "Cleared to XYZ airport, direct."  or Maybe "..as filed".

There are at least two actual answers to this question: what pilots are taught, and what ATC expects. In most cases, they're different. At a recent TRACON tour, I asked the controllers about this kind of situation (lost comms in IMC).
Most controllers have no idea what pilots are "supposed" to do under lost comms in IMC. They'll watch you on radar and clear as much airspace as they need to keep you safe. What they want you (us) to do is to be clear about your intentions and get safely on the ground as soon as feasible. So, for example, don't sit there and hold over the airport or at an IAF until your ETA: get to the destination—actually, get to the nearest reasonable airport with appropriate facilities for your aircraft and weather within your and your equipment's capabilities—and shoot the approach and get on the ground.
Lost comms in IMC is an emergency. Exercise your emergency authority as PIC to safely conclude the flight. "In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency."


text:
How safe are airplane tours of the Grand Canyon?
I'm curious as a complete layperson who's looking at scenic flights with Scenic or Papillon. I'm not afraid of flying on commercial airplanes, but this is a private, single-engine flight around the Grand Canyon. I think the company has had a bit of a history of crashes with its helicopter program over the past 15 years as well.
The tour is two 45 minute flights, I haven't booked it yet. Should I be worried?

Welcome to the site! There's some general information in this question but any operator that carries passengers has to follow a lot of extra regulations; it's not at all the same thing as a private pilot in his own aircraft. And even if an operator had some crashes in the past, if they've changed their aircraft, processes etc. since then, it's tough to make any meaningful comparisons.

It used to be worse. (Comforting, I know)
Back in the day (1956), commercial airliners traveling coast to coast would often give their passengers a little tour of the Grand Canyon on the way to their destination (air travel was still a novelty).  When a mid-air collision between two passenger planes occurred, the government invested in a $250 million upgrade (1960 dollars!) of the air traffic control (ATC) system. One could say that the crash resulted in the 1958 creation of the Federal Aviation Agency (now Administration) to oversee air safety.
One of the things the FAA did was create a Special Flight Rules Area (SFRA) around the Grand Canyon and make a specific chart just for the area. Additionally, they created approved commercial tour routes (see the orange routes below)

In addition to commercial sight-seeing tours being more regulated, there is a lot more training, documentation and procedures available for pilots with the main interest being safety. For example, the following notice is printed on the chart (References 14 CFR Part 93 Subpart U which gives minimum altitude restrictions, both for safety and noise abatement!)

https://skyvector.com/?ll=35.7929449938479,-112.79126822365794&chart=231&zoom=2
And of course, as mentioned in another answer, commercial operators, even if they are operating what looks like a "small private plane" are subject to increased mechanical inspections and regulations. One thing to look for when you arrive is the level of professionalism exhibited by the crew (it might just be a single pilot), but also the people checking you in and working with you to get you on your flight. There is something called a "culture of safety" in aviation that, while the unforeseen can always happen, if there is a culture of safety, preventable incidents can be minimized or eliminated.

Like many other fun things, there is going to be a risk associated with it. However, I would rank this risk as being pretty low.
I would like to split my analysis into two sections. (1) General Health Risks in the Grand Canyon and (2) Aviation risks in the grand canyon.
General Health Risks In The Grand Canyon
You are far more likely to die of heat exhaustion or falling in the Grand Canyon than you are from a plane crash. Admittedly, this might have to do with the quantity of people exposing themselves to the elements, rather than the number who take an airplane, but the point is that all manners of seeing the Grand Canyon will have a certain level of risk associated with them.
Aviation Risks in the Grand Canyon
As you noted, there have been several Helicopter incidents in the past. However, there have been substantially fewer Fixed Wing incidents.
From what I can tell, there have been two incidents in the past 10 years with regards to aviation tours in the Grand Canyon area. In one incident there were no injuries. In the other, there was one fatality and several other minor injuries.
Try comparing that to general automotive statistics!
My Advice
An air tour of the Grand Canyon sounds like a great time and the risk of injury is negligible. In fact, it might even be the safest method to see the Grand Canyon, in comparison to helicopters (higher incidence rate), Mule's (substantial number of deaths per year), and hiking (risking exposure to the elements).
In the past 10 years only one individual has died on one of these Grand Canyon air tours. I would personally take those odds and enjoy the view!

Hmm, your "statistique" sounds wrong. Far less people died of airplane accident on the grand canyon because far far far less people take the plane than go on foot.
That said, I agree with your conclusion

That's a good point @Antzi. At a tertiary glance I couldn't find any comparisons in usage. I'll make some edits regardless.

Thanks for the advice. I guess you're right that most of the accidents were helicopters. I'm not planning on extensive hiking of the canyon either (maybe a brief ATV tour).

Flying over the canyon is relatively dangerous. Over the years there have been 65 fatal crashes of various aircraft in and around the canyon causing a total of 379 deaths. All the deaths are either known or believed to have been flights involving sight seeing.
If we subtract out the 128 deaths from the 1956 crash, that leaves 251 deaths in 60 years, or approximately 4+ deaths per year. If we estimate that approximately 500,000 people take an air tour every year, then the chance of dying on an air tour is about 1 in 100,000 visitors. The overall death rate for all visitors, air and foot is 1 in 400,000 (National Park Service statistics).

Sources for your figures would make an excellent addition.

Hey Tyler, just wondering -- are you talking fix winged aircraft, or helicopter, or both? I'm just wondering because it seems like most crashes are helicopter related, but I'm not sure

The fatality count is for all aircraft.


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Turbo-electric engine vs high by-pass-ratio Turbo fan, which config. would seem more efficient? (Liquid Hydrogen Fuel)
Would be a turbo-electric config using 2 turbofans as generators for a 150 pax. aircraft more efficient than a very high bypass rationed Turbofan that burns hydrogen?
If not, then why are all companies like Airbus, Rolls Royce and Safran etc. working towards this?
Also, why would they just use their Highby pass Turbo-fans, that ways they don't have to invest billions and also have very high efficiency and less pollution (CO2, Nox, etc.)?
If we can argue about 15 years down the line, what would be a better solution? And why?

It's called greenwashing. Everybody in the industry knows that hydrogen and electric propulsion are impractical for airliners, but the press, woke activists and politicians don't listen but think they know it better. Hence the theater.

@Peter Kämpf - can you cite a source for the impracticality that everybody in the industry knows.  Or might there be an analogy to using a petrol engine to power an aeroplane in 1900?

@Frog Simple physics seems not convincing, so why don't you read some of the answers here?

@Peter Kämpf - with no disrespect to your standing in this forum and elsewhere, citing your own statements as evidence that everyone in the industry knows something is not entirely compelling.  I understand that there’s no arguing with the state of the art regarding physics, but perhaps you could clarify whether you think that electric airliners will ever be viable; if so then it follows that the ongoing efforts in this direction are justified.

@Frog I linked to questions, not answers. Feel free to read the insights of others, too. I'm not holding you back. Now you ask about electric airliners ever to be viable. From first principles, an energy source that uses resources which are readily available at the place of consumption will always be superior to one which needs to carry all energy along with it. So an electric airliner might become viable one day but will always be at a disadvantage to one which uses a chemical reaction with oxygen. Regarding development: Put the effort in a field where it pays sooner, like electric cars.

@Peter Kämpf - hesitant as I am to continue shaking this particular tree, are you perhaps equating electric power with battery power?  Something like an ethanol fuel cell would indeed dispose of its fuel load progressively in flight.  Although I note that the OP is asking about turbo-electric propulsion, which could be powered by normal jet fuel.

Turbo-electric configurations do not offer any meaningful advantages for commercial airliners.

Aircraft engines have extremely high power-to-weight ratios. These would be greatly degraded by adding motors and generators.
For instance, the RR T406 offers power in excess of 10 kW/kg. Large turbofans are even better. Most electric generators and motors are worse. The best have the same power-to-weight, but since they only transfer power, this increases the weight of the engine system by a factor of 2.5-3.

Wings are already the optimal location for both the generator and the propulsor.
You want your heavy engine where the lift is created, and that's the wings. You want your propulsors away from the fuselage, and that's either the wings or the tail.
Thus, there is no need to move the power any distance.

Hydrogen is a suitable fuel for turbofan engines and requires no other intermediate devices to convert it to thrust.
There is no significant need for hybrid airliners, as there's no stops to recover energy in flight.
Weight means fuel burn. Engines are heavy: in an A320neo, for example, they take up 14% of the weight. Increasing it 2.5x will make the aircraft 20% heavier. After adding payload and unusable fuel, this results in 15% more fuel burn, if the motors and generators were perfectly efficient.
Since they are not perfectly efficient, a naive replacement would result in even worse fuel consumption. This could be offset by perfecting propulsor size, speed, and placement, but the end result is still that a turbo-electric aircraft will be less efficient than a similar turbofan aircraft.
As to hydrogen itself, it is not the best aviation fuel. However, it is usable. The overall energy efficiency will be worse, due to the loss of cabin space to tanks. Whether that can be offset by clean production is a question outside of aviation.
Regardless, a 15-year horizon is so short that it can be safely said that hydrogen or electric or hybrid airliners will not be anything more than concepts and experiments in this timespan. 75 years, that could be a topic for debate, on appropriate sites.


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Negative number in ARINC-429
I'm a little bit confused by representation of negative number in ARINC-429.
Let's consider the following example:

Significant bits is equal to 7 (it does not count sign bit),

Resolution is equal to 1,

DATA section has to represent -1 value.
Initially I thought that DATA section is represented as follows:
1 1 1 | 1 1 1 1 | 1 0 0 0 | 0 0 0 0 | 0 0 0 0

But I'm confused by sensor documentation. There sign bit is not in DATA section and I started to think that maybe bits 29-11 should look like that:
1 0 0 | 0 0 0 0 | 1 0 0 0 | 0 0 0 0 | 0 0 0 0

Which way of thinking is correct?

BNR labels that can be negative are represented in 2's complement form
2.3.1.1 Numeric Data

The Mark 33 DITS should accommodate numeric data
encoded in two digital languages, (i) BNR expressed in
twos complement fractional notation and (ii) BCD per the
numerical subset of ISO Alphabet Number 5

If your label is indicating 7 significant bits and an LSB of 1, your range must be +/-128. Bit 29 is the sign bit, and the data bits work down from there.

-1 = 1 1 1 | 1 1 1 1 | 1 0 0 0 | 0 0 0 0 | 0 0 0 0


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What is the exact meaning of "manoeuvring" when said by ATC in reference to traffic?
In the UK, when receiving a basic service, sometimes the ATC unit passes traffic information. They may say it like this:

“Traffic to your three o'clock, similar level, C172 manoeuvring.”

What exactly is the word “manoeuvring” conveying? Is there a defined point where an aircraft is manoeuvring and when it is not?

Welcome to Av.SE!

I haven't been able to find a precise definition in either the CAA or the FAA's materials. However, as I understand it, traffic that's "maneuvering" is traffic that's not going anywhere in particular.
If someone's flying in order to get somewhere, generally, they're going to be at a specific altitude flying in a specific direction. Course changes will be rare, and generally only occur at specific navigation points, such as VORs or VFR Reporting Points. Such traffic is easy to predict, so ATC can give you a specific heading and altitude for it, and you can assume that that information will be valid for a while at least.
On the other hand, someone that's flying for the sake of flying (e.g. someone doing aerial sightseeing, a student pilot building time, someone checking out a new aircraft, etc.) is going to be a lot harder to predict. They may turn, climb, or descend with little to no warning. That's what I've always understood "maneuvering" to mean: a warning that this traffic is unpredictable, so stay away if at all possible.

Students are most likely learning or practicing maneuvers, not just building time for the heck of it.

As an FAA controller, this is exactly what I mean when I say "maneuvering:" traffic that is turning or circling or otherwise moving in an other-than-Point-A-to-Point-B manner. If the traffic is going steadily in some direction, we describe it absolutely or relatively: "westbound" or "converging." (+1)

Traffic that's maneuvering could be doing any one of several things, ranging from flight training to a post-maintenance check flight, or someone doing aerobatic practice. It's not doing any one thing in particular and may change direction unpredictably and without warning. The alternative to maneuvering is traffic moving in a straight line, perhaps transiting to a practice area, or flying between airports. This type of traffic is much more predictable. Essentially, maneuvering traffic is traffic that can and probably will change direction often. For this reason, if possible, it's likely advisable to avoid that aircraft.


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Do airline pilots prepare and are aware of possible emergency landing sites around airports they are taking off in case of complete engine failure?
Do airline pilots prepare and are aware of possible emergency landing sites (like farm fields, wide highways, lakes etc.) around airports they are taking off in case of complete engine failure at a low altitude without sufficient energy to turn around and land? It is unlikely scenario but if it happens there is very little time and it seems to me it is not very time consuming to just check the map during flight preparation. If it is not a mandatory procedure my guess would be that some pilots do this anyway, right?

You use airline and engine (in singular), so your question is mainly on small single engine commercial aircraft, or are you implying also on large multi-engine aircraft?

Be aware that the term "ditching" refers specifically to a forced landing on water

I am skeptical that pilots review the surrounding area for a place to do an emergency landing. With small airplanes, from the ground to a certain height the right answer is to return to the runway, then above that it's to land straight ahead, no matter the obstacles, and above that the right answer is to return to the runway for a downwind landing. Airliners have specific speeds where if they have a failure then below that speed they stop on the runway and above they take off fully and return to the airport.

"from the ground to a certain height the right answer is to return to the runway, then above that it's to land straight ahead" isn't it the other way around @KennSebesta? Up to a certain height, you land straight ahead, while higher you've got the energy & gliding distance to make the return to the runway?

@FreeMan I think what Kenn meant was that you can land on the runway again just after liftoff, especially when the runway is much longer than you need, because you are still over the runway. Then comes the period of no-return and then once your high enough you can turn around to land on the same runway but in the other direction.

@FreeMan, yup, Bianfable's interpretation of my comment is correct. Apologies for the confusion, in retrospect I definitely see how my sentence was awkwardly written.

Makes much more sense that way, @KennSebesta. Thanks to Bianfable for the clarification.

The basic answer is no. All failure mode scenarios assume a single engine failure with a departure and climbout on the remaining engine. Double engine failures are not accounted for because the mathematical probability of a simultaneous double failure is beyond the 1-in-a-billion threshold for a single event initiated by a component failure that leads to loss of the airframe.
Double engine failures on takeoff are always due to an external single source, like a flock of geese, or fuel related. Neither of these eventualities are catered to in design or procedures, being extremely rare relative to the many millions of hours flown each year by the world wide airline fleet.

I'm contesting the "one in a billion". I'd say it's an order of magnituge smaller, which would still make it extremely rare though.

In risk analysis for design, there are 4 categories; Minor (minor crew workload impact), Major (serious crew workload impact), Hazardous (aircraft seriously damaged and/or somebody gets hurt or killed), Catastrophic (everybody gets killed), each with probability thresholds. The minimum probability for Catastrophic is 10⁻⁹. If the probability of a Catastrophic loss following a single element failure, in the probability analysis, is higher than that, you must add redundancy to get it below the threshold. This is why you will have triple redundancy in some systems.

I do realize that, but it is my non-vefified recollection  that all engines out -scenarios during takeoff are more frequent than once every 25 years.

The scenario we are talking about is TWO engines going out for mechanical reasons on the same flight. The frequency of that is beyond 10⁻⁹.  All-engines-out scenarios are ALWAYS from a single common source, as I said. Water, ice, birds, fuel, yadda yadda yadda.  You just don't get something breaking randomly on #1, and something breaking randomly on #2 on the same cycle.  ETOPS would not be possible if that was the case.

I read the question in a way broader context. IMO simultaneous mechanical failure was not specified in the question as it stands at the moment, so any reason for all engines out should apply here, be it fuel, mechanical or FOD related. There is not much point in asking about just mechanical failure scenario, since there is no difference as to why power is lost, and the full power loss due to separate but simultaneous mechanical failure is ridiculously unlikely as you stated (I'm not contesting that specific case).

"Complete engine failure at low altitude" I take to be something with the engines. The other things are external phenomena, even fuel, like that event in Indonesia that was traced back to contamination of the fuel tanks at the airport during construction. So rare, basically a Black Swan, it's not something to devote time and energy to mitigating. Think about it. When doing a departure briefing, you think a crew's going to include all the eventualities for a double failure from hitting a giant flock of geese? It means researching all the terrain around the airport. Nobody has time for that.

An engine may fail due to internal or external factors. The question does not specify an internal mechanical failure.

If you say so. As I said, "external factors" are Black Swan events not accounted for in design or procedures.

For the record I have the highest respect for your knowledge and contributions to this site. In this case our points of view are different. I look at this question as if I was the pilot. From the front row it makes no difference why the engines fail. Black swan events may not be considered in engine and systems design, but they are a statistical reality for pilots.

My point is, absolutely nobody considers this in a departure, & it's not a consideration under any procedural protocol in the industry. You're working from IFR airport charts & maps that do not even show terrain details except as terrain collision hazards in mountains. Even VFR charts don't show terrain details that would be of any use. A zillion variables you'd have to account for in a briefing, & the data just isn't available to the crew, for an event that happens once every few years. Airliners that've dead sticked successfully did so b/c the opportunity presented itself in the moment.

I agree on this. All engines out stats not so much :)

Just to clarify, yes, my question wasn't about internal mechanical failure but complete failure regardless of internal/external factor. I figured that it is unlikely and won't be a part of departure briefing, was more curious if some pilots take terrain (and possible crash landing sites) into account as their own mental preparation before flight.

@MangoPanda21 no doubt that some do informally, esp when there is a lot of large bird activity. It just wouldn't be part of any standard evaluation or briefing.


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AS8003 Altitude Encoders: How are readings from silicon pressure sensors converted to pressure altitudes?
Encoders such as the ACK A-30 use uncompensated silicon pressure sensors (e.g. MPX100 series according to this video) which are kept at a constant temperature. I presume they are heated so as to stay on the same voltage to pressure conversion line (Figure 3 MPX100 documentation). Is this presumption correct? More importantly, however, I was curious how the conversion from pressure to pressure altitude is carried out. I have come across this formula, but I was not able to find any documentation that specifies what conversion calculation/look-up table is actually used. Perhaps this information is contained in AS8003, but that document is behind a paywall.

The conversion pressure-->voltage (analog output) is done by a silicon diaphragm which is elastic, and piezoresistive strain gauges measuring the deformation. The gauges are sensitive to temperature, so the heating.

Thank you for the description and for the resources.

Altitude encoders are relatively simple devices. They are designed to be as inexpensive and reliable as possible. They are so cheap that if it fails, buying a new one is cheaper than a repair (and you get a new warranty.)
But on to your question of design. It's basically a sensor and linear data flow from the transducer to the output. And most of the basic ones used Gillham output coding on nine to 11 parallel discrete lines.
The static line input is connected to the pressure transducer. We bonded the back of it to a voltage regulator and covered it with a foam insulating block. We referred to this as the oven. Heat from the voltage regulator heated it to about 130 deg F. There was a thermistor controlling the voltage regulator to maintain a constant temperature. Doing this avoids having to compensate the transducer output to a variable temperature. You heat it above ambient as it's easier to maintain a constant temperature as the external temperature varies.
The analog voltage output of the transducer is then fed into an A/D converter. The digital output then goes to a custom ASIC that is essentially a lookup table. During calibration the table is populated with the Gillham code for the voltage range associated with the altitude range. Avionics shops have a test set that can set the pressure output line to a specific altitude calibrated to the ICAO standard atmosphere (basically, the reverse of the encoder.) And to answer your other part of the question, the standard atmosphere is defined using a table.
For the parallel output the Gillham code is put through a serial-to-parallel converter to set the output discretes. Some more expensive units would provide the serial output in ARINC 429 or RS232 formats.
To be clear, you don't really care what the voltage output of the transducer is at a specific pressure altitude as long as it is relatively linear across the range. You provide a calibrated altitude source to the unit and read the voltage output and then plot it against altitude. You then build the lookup table setting the Gillham code for the range of voltages. An example would be the voltage range output from a pressure altitude input of 3950 feet to 4050 feet will be set to the Gillham code for 4000 feet [ 0 0 1 1 1 1 0 1 0 for the A1 A2 A4 B1 B2 B4 C1 C2 C4 lines.]

Have a look at the ICAO standard atmosphere (Doc 7488). It contains formulas and tables for conversion between altitude and pressure and vice versa, but only for the standard atmosphere (1013.25 hPa /29.92 inHg). For QNH correction there is a separate formula, which is documented in AS8003 and other sources (I can't find a good public source).


text:
Do rivets on airframe need special sealant to be airtight on pressurized airliners?
Do rivets on airframe need a dedicated sealant, e.g. epoxy, to be really airtight on a pressurized airliner, or is the expansion of the rivet shaft already sufficient?
As a side note, how are carbon fiber panels joined with aluminum or titanium panels?

Just FYI its best to ask one question per each posting - they're related questions, but different.

I banged rivets on a production line long ago.  The countersunk rivets used in the pressure hull depend on expansion of the shaft, but some rivets also have a slightly larger radius where the shank flares out into the head compared to a standard flush rivet, which forms a tighter seal when the rivet is set.
You don't actually apply sealant to the rivet itself. The sealant, which is a crazy-sticky goo stuff (not epoxy, it cures to a hard rubber consistency), gets everywhere when you are shooting rivets on the pressure hull because the faying surfaces (the overlapping metal to metal surfaces) are coated in sealant before assembly, which gets in the rivet holes (the sealant is a pain in many ways; it acts like a lubricant if it gets on the skinny end of the rivet and makes it easy to dump the rivet over when you buck it).
Carbon fiber panels are usually joined to metal with bolts or Hi Lites or similar rivets, with some sort of insert or doubler of stainless or titanium in the carbon to distribute the loads.  Sandwich floor panels for example, typically use a titanimum insert bedded into the sandwich with epoxy resin, through which the fastener goes.  Carbon against titanium is fine, but if joining carbon to aluminum, you MUST have an insulating material to separate them because they live at opposite ends of the galvanic scale.  Carbon touching aluminum = lots of corrosive fun.

Back in the day when cigarette smoking was allowed on most airliners, the pressurized ones would leak until they had a few months of flying time on them. when torn down for repair and inspection it was discovered that the leaky seams in the pressure hull were caulked tight with condensed cigarette smoke...

Yes basically the same as sealing your driveway cracks with tar.  Cigarette tar played havoc with outflow valves, but the most damage was done to avionics.

were you an avionics tech? what planes did you service?

No I was a hydromech engineering guy and also did some flying. CRJs.  Retired now.

@JohnK If the carbon is in contact with titanium and titanium then touches aluminum, wouldn't it still corrode because titanium is a conductor as well and the cell is completed?

Depends where they fall on the galvanic scale. Graphite is a strong cathode and the more anodic the metal is (like aluminum or zinc), the stronger the corrosion tendency when moisture and the graphite cathode is present. Titanium is at the other end, strongly cathodic like graphite, and is almost as corrosion resistant as gold as a result.


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How do flaps deploy and stow with very large wing flex?
On large airliners, the wings are generally of the high aspect ratio types and hence very flexible. Now the flaps are attached to wing only through a series of tracks, and as the wings flex, these tracks change relative positions to one another as well. How is the flap designed so that it can ride on these tracks regardless of their positions? I scoured the internet for answers and the only vague one I got is this description

One of the flap tracks positions the flap and all others absorb horizontal displacement.

Intuitively this is like designing a door that can open and close with a doorframe that is sometimes straight and sometimes crooked. Is the door also flexible itself?
This question applies to not just flaps, but to spoilers, speed brakes and leading edge slots or drooping leading edges as well. How are they designed?

Are you familiar with rod end bearings?

If the flap is on 3 tracks, it flexes with the wing and there is compliance built into track system.  If the flap is on two tracks, it'll stay straight as the wing in front of it curves.  But in a two track system, the panel is short enough that the wing curvature is negligible to the flap.
What that statement means is that with a 3 track panel, as the flap flexes with the wing, the total distance between the 3 tracks gets longer and shorter by some value, say an eighth or quarter of an inch or whatever.   To accommodate this the center track is used to control the lateral position of the panel, while the inner and outer track has lateral side play built in to the roller system so the change in distance doesn't cause binding in the outer tracks.
Slat systems are the same. The center track has guide rollers that locate the slat and the outer ones are "floating" laterally by having larger roller clearances.  Other panels on the wings like spoilers that are much shorter are able to get away with just using spherical bearings that allow some compliance as everything moves.


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What resources can direct me to real estate with landing strips?
I am looking for a website or places to look at estate / personal residences in PA, DE, MD, VA that have landing strips already in place.

There seem to be many, however, some of those "landing strips already in place" will no doubt be public airports that border the property or shared private community strips that aren't generally inviting the public.

aviationacres.com
aviationhomes.com
hangarnetwork.com
airportairparkhomes.com


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What are the fuel requirements for Canadian flights?
I am aware of the "US Flag Jet", "Piston" and "Domestic" policies in the US, and the ICAO policies. Is there a specific requirement in Canada for domestic and also international flights? Does Transport Canada have their own regulations, or do they use the ICAO or US ones?
I'm asking this for use in simulation but I'd imagine this is also a valid question in the real world.

@mins yes, I mean minimums and reserves. And having trouble finding a link to these. I know they're options in PFPX, a popular flight planning and dispatch tool for FSX and P3D.

The applicable regulations are found in this circular. See also CAR 705.25, Fuel Requirements, Operator Responsibility.


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How much thrust and fuel are required to get a B767 moving from a complete stop?
How much thrust is involved, and how much fuel is burned, to get an aircraft like a Boeing 767 - or something similar - moving from a complete stop?
Recently, I was on a 767 that took the "scenic route" around the DFW airport trying to get to a gate.  We were on the tarmac for an unusually long time, and had multiple stops and starts.  I was curious how that might have affected fuel costs as opposed to a shorter time on the tarmac and a more direct path to our gate.

Your definition of "average size airplane" and mine are very different.

If you have any insight into what it takes for any particular plane, that would be a start...I'm not necessarily looking for the specifics of getting a 767 moving.  I just gave that as a reference for why I'm asking the question.

@RyanMortensen: It seems expensive to release a plane from the gate, and then have it to stop moving and restart multiple times before reaching the runway, because of the congested taxiway. I think the question is a good one (+1), and actually the answer may confirm other methods, like delaying engine start and taxi, would be better.

@mins Yeah, it's a good question.  I just thought it wasn't clear at first.

It depends on what the aircraft is doing. If you literally just want to "get the aircraft moving", then all you need to do is supply enough thrust to overcome the static friction in the wheels (bearings and contact with the ground) and any headwind. So what are you actually asking? For example, how much extra fuel is burnt when an aircraft taxiing at V miles per hour stops, waits for T seconds and then accelerates back to Vmph, compared to when it just taxis?

@mins - on the other hand, having the plane occupying the gate may well cost money, as well as increase congestion since an arrival cannot get to the gate to start unloading, causing delays for other flights, etc.

This research paper may be of interest for you. According to their data the 777 burns about 250Kg of fuel on taxi on average with a few data points showing burns well over 700Kg of fuel. This paper which quotes the previously linked paper talks a bit about different fuel saving methods and their impacts, like single engine taxi and what not. In short taxi distance will always burn a bit more fuel, the primary concern is taxing for takeoff (since you don't want to cut into your estimates). Once the plane is back on the ground it becomes less of a safety concern as running out of fuel becomes an inconvenience (that a tug can solve) and less of flight risk.
Here is an interesting paper on fuel burn rates if you were to extend a runway by 500Ft. They provide data/estimates for many air frames.


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How are bids packages and awards generated?
There probably is no short answer for this. Crews out there, how do you bid and how are you rewarded? Are you always satisfied with your lines? Can someone also explain in brief from a system point of view, if you happen to be a crewscheduler. Thanks

This looks like 3 different questions that would get better answers if asked individually.

This differs from airline to airline, at a large ME carrier the staff is divided in groups based on their personality. People from each group are randomly assigned to flights. Then there is a list where you're at a certain position, with each flight you take you move one spot higher on the list. The higher you are on this list the more they will take your preference for a flight into account. Lets say that this list has 7 positions, once you've hit the top you are moved back to the bottom of this list. Then with each flight you're going one step up in the list again. So after each 7 flights you have the flight of your preference. But say that you're almost at the bottom and file a preference for a very unpopular flight then you have a high change they will schedule you on that flight.